This invention relates to an apparatus for measurement of changes in the length of a specimen.
A wide variety of gauges for measuring the changes in the length of a specimen are known in the prior art. These gauges include, for example, vernier calipers and micrometer calipers. A particular gauge which may be used to measure small changes in the length of a specimen was described in U.S. Pat. No. 2,177,605. With that apparatus, very accurate measurement was possible. However, that apparatus was limited to measuring the change in the length of specimens having a very narrow range of lengths and thus it is of relatively limited use.
It is an object of this invention to provide a gauge with the capability of being used to obtain a very accurate measurement of small changes in the length of a specimen and which is suitable for use with specimens having a variety of lengths.